Treatment of carbon black with oxyhalides



June 9, 1953 M. R. CINES ET Al.

TREATMENT OF' CARBON BLACK WITH OXYHALIDES Filed Nov. 6, 1950 INVENTOR. M. R. CINES BY W T lNELSON ATTORNEYS Patented June 9, 1953 TREATMENT F v(JAR/BON BLACK WITH *()XYVHALlDES 'Martin R; Cines and William T. Nelson, Bar-isles.-

ville,` Okla., assignors to Phillips 'Petroleimx "Company, -ra corporation .of Delaware implication,November 6, 1950, Serial Nal-94,292

This invention vrelates "to treating carbon black. In. one .of .its more specific aspects this invention relates to the reduction of the pH of carbon blacks, :and specially relates to A.the treatment of high pH f-urnace fcarbon black with oxyhalides of nitrogen, phosphorus and sulfur, or mixtures thereof, whereby the pH of the furnace carbon i black is reduced.

This is a continuous-'impart off our application,

Serial No. 136,820, filed January 4, '1950, now abandoned.

"The high pH of furnace `carbon blacks lis not in itself objectionable, but when 'these blacks are used in compounding rubber, particularly ,natural rubber, the rubber mix iordinarily has an undesir.. ably low Scorch time which gives rise to diiiiculties during the mixing and forming-stagesof processing. Rubber stockswhich Scorch during mixing. calendering, extruding molding, etc. fare vdiiiiciilt to vhandle and many times result in loss Iof `the rubber mix. Lowering the pH of thefurnace-carbon blacks, such as high abrasion furnace carbon blacks (HAF blacks), high modulus furnace carbon blacks (HMF black-si, very fine furnace carmaking the treating processes undesirable `from Y the standpoint lof equipment Areduirements :an operational diiiiculties. f Y

.ThepH ofa carbon black. is determined by boiling ydistilled water containing vva sample of .the black vfor about 15 minutes, allowing the carbon black to settle, decanting the water, and wmeasur ing the .pI-I of the slurry of ,carbon black re.- maining.

.We have now discovered vthat the pH of carbon black can be reduced by treating same with ,oxy.; halides of nitrogen, phosphorus and sulfur. .MiXJ- tures of two or more oxyhalides can be used .suce` cessfullyinthe process of our invention. Nitrogen oxyhalides which can )be used in the practice of ,ourinvention are, for eXample,'NOC1,'NOF, TNOBr; NOBra, NOzCl and NOz'F. Sulfur oxyha'lides which can 'be used "in the ,practice of our 'invention are, 'for example, SOClz, SO2C12, SOBrz, SOM, s021532 and SOBrCl. 1?hosphorus` oxyhalides a10- pl'icablein thepractice of our invention are, for

example, POCla, POBr3, POFS, POBrClz and POBrrCl. Other compounds capable of yielding the oxyhalides under the reaction conditions can be used where the products formed are not deleterious. The new furnace carbon black treating compounds of the process of our invention allows treating at relatively low temperatures, and permits versatile operation, that is, the pH of furnace carbon blacks having a pH of from 8.5 to 10.1 can be lowered to a pH as low as 3 or 4, or intermediate pH values can be obtained, as desired, by adjustment of the treating conditions.

It is an object of this invention to provide a method to lower the pH of carbon blacks. parties ularly a highpHvfurn-ace carbon black..

Itis another object of this invention `to provide new treating compounds to ,be use d treating carbon blacks, particularly high 10H furnace rear*- bon blacks, to lower'thepH of the carbon blacl.

Other objects and advantages of the process of this invention will ybecome apparent, to oneskilled inthe art, upon reading this disclosure.

Thedrawing which accompanies andisa part of this disclosure is a 4,diagrammatic `flow vsheet set.- yting :forth a speci-lic .embodiment -of the process of our invention as IApreferably ,carried out in a usual pel-leting mill.

Ihe process of our invention Lis practiced by contacting the carbon black .with thenxyiialdes, which :is preferable, in the presence :of .a dihient gas, fSuch-as air, nitrogen, inert .flue gas, etc. The `oxyhalides can be carried by the diluent gas used .in treating in concentrations .of .from :0.09.1 .to about 15 volume per cent, though. usually fan .amount betweenal and 11 volumeper cent. The Quantity of treating sas used can be from 1 vto 50 standard cubic feet ,for each pound .of black. fusils ally from ,to 11,5 standard-cubic feet perk-pounder hlaclr. Treating .temperature is usually andersterably between atmospheric and 400 F. Lower temperatures :can be used, but :this normal-1Minwolves refrigelation vand is not necessary to give goed .and -efcient results. Treating ,times fear; ,vary from :about 1 minute -upfto .24 hoursor longer, the typeof apparatus used in treatment determin, ing .to a ,great extent the optimum time of treatment. Treatment `at atmospheric pressure ris .sat-- isfactory, though higheror lower .pressureseanibe used. ,The .apparatus and .method .disclosed .by R. A. Ebel in application. -,Serial .Number 125,332. lfded November 3 A1'349, .can .advantageousLv ,be .used Yin -canary-ing .out the treating .method -`di v our invention.

Qur Jprocess can be practiced before, during, or after pelleting of the carbon black'. In most cases, however, carbon black is marketed in pellet form, and carrying out the treatment in the pellet mills necessitates adding only a very small amount of additional equipment and produces 4 perature, catalyst concentration, time of treatment, and other conditions should be within the ranges previously discussed, though these were not repeated in the description of the above spequite satisfactory results. The treatment can, cie embodiment. however, be practiced using loose black or pellets, The following are examples of our invention treatment being accomplished in fixed or fluidized rwherein a furnace carbon black having a pH of bed or with the carbon black suspended in the 9.1 (an HAF carbon black) was treated with air treating stream. Batch or continuous operation and nitrogen containing various oxyhalides. It can be utilized. It is preferred that water andv is to be understood that the temperatures, preswater vapor be substantially excludedfrom the sures, concentrations, materials, etc. set forth in treating system. the examples are not to unduly limit the scope of The attached drawing is a flow diagram of one our invention. specific embodiment of the process of our inven- Eight runs were made under the conditions and tion as practiced in a, pelleting operation. Howwith the results set forth in the following table. ever, it is to be understood that the drawing or A circulating suspended bed of the carbon black following discussion, referring to the drawing, was contacted with the treating gas in a cylinare not to unduly limit the scope of our invention. drical vessel. The gas was passed through con- Referring now to the drawing, loose carbon tinuously and not recycled.

l Mol Percent Degassed Treating Treatmg T Oxyhahde pH of Run I\o. lreatmg Gas Temp. Time atraer 0 F @mi Tails P0013 1 Pools-Air 0.03 75 30 5.2 2 PoC13-purieed N, 0. 03 75 30 5.8

soon 3 sooir-Air 0.15 75 30 5.0 4 soon-purified N2 0.15 75 30 6.8

' SOQCIQ 5 solely-Air 0. 35 75 a0 s. s e so2o12-puriaedN 0. 35 75 3o 4.0 Noci 7 Noci-Air 0.08 75 10 7.7 s NOCI-purified N1 0.08 75 10 7.5

black recovered from a furnace process is conducted through line Ill and is joined by recycle pellets from line I2. The total stream is then conducted into pellet mill via line |45. A diluent gas, such as fresh air, is conducted through line I6 and is mixed with the oxyhalide added This same carbon black when treated with air or nitrogen alone under these conditions is substantially unaffected by the treatment.

As will be evident to those skilled in the art, various modifications of this invention can be made, or followed, in the light lof this disclosure through line I8, the total stream then is passed lo and discussion, without departing from the spirit into pellet mill 20 via line 22. The pelleting operor scope rof this disclosure or from the scope of ation is ordinarily conducted within the limits the claims. of the previously-discussed reaction conditions We claim: suitable for treatment of the black in the presl l1. A process for treating a high pH furnace ence of the oxyhalide to reduce the pH, and thus carbon black having a pH of from 8.5 to 10.1 to no substantial alteration of the usual pelleting substantially lower its pH and thereby increase operation is necessitated. In the rotating pellet the scorch time of a rubber mix compounded mill, the bed of carbon black is turned over a therewith which comprises. ycontacting said cargreat many times, resulting in thorough contactbon black with an oxyhalide selected from the ing of the black with the oxyhalide-containing 50 group consisting of nitrogen oxyhalides, sulfur treating'gas, thereby reducing the pH or the black. oxyhalides, phosphorus oxyhalides, and mixtures The gas and rtreated carbon black pass from the thereof, at a temperature of from atmospheric to loutlet of the mill into separating drum 24. The 400 F. and recovering a resulting carbon black pelleted carbon black is collected in the bottom having aA substantially reduced pH. Aof drum 24. The resulting pellets are removed 2. The process of claim l wherein said contactfrom drum 24 through line I2, a portion of vthe ing is carried on while Said'oxyhalide is in gaseous stream being drawn off through line 26 to product form diluted by a diluent gas. storage, and the remainder, if recycling is neces- 3. A process for treating a furnace carbon sary lor desirable, is conducted to line l0 via line 60 black having a pH of from 8.5 to 10.1 to substan- `I2 and recycled to pelleting mill 20. v tially lower its pH and thereby increase the The gas which is separated in drum 24 from the Scorch time of a rubber mix compounded theretotal effluent of the mill, which is COmprised of with which comprises, contacting said carbon 'diluent gas and the OXyhalide, iS reIIlOVed through black with from 1 to 50 standard cubic feet per line 23, and iS usually diSCal'ded in Daft through 65 pound of said carbon black of a diluent gas con- -line 30. The remainder of the gas is passed taining frm 0,001 to 5 volume per cent of an through line 32 t0 line 22, joining the fresh air oxyhalide selected from the group consisting of and OXYhalde, and thence recycled t0 Delletng nitrogen oxyhalides, sulfur oxyhalides, phospho- Vmill 20. A blower (not Shown) iS usually necesrus oxyhalides, and mixtures thereof, said consary in Ordelto recycle this gas t0 pelletng mill 70 tacting being carried on for a period of time of V20. In 'Some applications t'may be desirable to from 1 minute to 24hours at a temperature of ldiscard all thegas removed from separating drum from `atmospheric to 400 F'. and recovering a re- 24, in'which case the valve in line 32 is closed and sulting carbon black having a substantially reallpthe gas. is discarded through line 30. duced pH. 1 f Inthe process as described, the treating temh75 A 4. A process for treating furnace carbon black having a pH of from 8.5 to 10.1 to substantially lower its pH and thereby increase the scorch time of a rubber mix wherein said carbon black is used which comprises, contacting said carbon black with from 5 to 15 standard cubi-c feet per pound of said carbon black of a gaseous mixture comprising from 0.01 to 1 volume per cent of an oxyhalide selected from the group consisting of nitrogen oxyhalides, sulfur oxyhalides, phosphorus oxyhalides, and mixtures thereof and a diluent gas, said contacting being carried on `for a period of time of from 1 minute to 24 hours and at a temperature of from atmospheric to 400 F. and recovering a resulting carbon black having a pH within the range of 3.0 to 7.5.

5. The process of claim 4 wherein said oxyhalide is NOCI.

6. The process of claim 4 wherein said oxyhalide is SOClz.

7. The process of claim 4 wherein said oxyhalide is SOzClz.

8. The process of claim 4 wherein said oxyhalide is POClz.

9. The process of claim 4 wherein said oxyhalide is NOBr.

10. A process for treating loose furnace carbon black having a pH of from 8.5 to 10.1 to substantially lower its pH and thereby increase the Scorch time of a rubber mix compounded therewith which comprises: passing said loose carbon black into a pelleting zone; introducing a gaseous mixture comprising from 0.001 to 5 volume per cent of an oxyhalide selected from the group consisting of nitrogen oxyhalides, sulfur oxyhalides, phosphorus oxyhalides and mixtures thereof and a diluent gas into said pelleting zone in an amount of Afrom 1 to 50 standard cubic feet per pound of said carbon black and therein directly contacting said gaseous mixture and said carbon black for from 1 minute to 24 hours at a temperature of from atmospheric to 400 F. while pelleting said carbon black; withdrawing resulting gases and treatedcarbon black from said pelleting zone and separating same; withdrawing a portion of resulting gases from the system and recycling the remaining portion to said pelleting zone; and withdrawing a portion of resulting treated carbon black pellets from the system and recycling the remaining portion to said pelleting zone.

11. The process of claim 10 wherein said oxyhalide is NOCI. 12. The process of claim 10 wherein said oxyhalide is SOClz.

f 13. The process Vof claim 10 wherein said oxyhalide is SOzCl.

14,. The process of claim l0 wherein said oxyhalide is POCla.

15. The process of claim 10 wherein said oxyhalide is NOEBr.` v MARTIN R. CINES. WILLIAM T. NELSON.

References Cited in the flle of this patent Villers, D. S., Journal of the American Chemical Society, Vol. 69 (1947) page 214. f

Zapp, R. L., Ind. Eng. Chem., Vol. 36 (1944), page 128.

Braendle et al., India Rubber World, Vol. 119, Oct. 1948, No. l, pages 57-62. 

1. A PROCESS FOR TREATING A HIGH PH FURNACE CARBON BLACK HAVING A PH OF FROM 8.5 TO 10.1 TO SUBSTANTIALLY LOWER ITS PH AND THEREBY INCREASEE THE SCORCH TIME OF A RUBBER MIX COMPOUNDED THEREWITH WHICH COMPRISES, CONTACTING SAID CARBON BLACK WITH AN OXYHALIDE SELECTED FROM THE GROUP CONSISTING OF NITROGEN OXYHALIDES, SULFUR OXYHALIDES, PHOSPHORUS OXYHALIDES, AND MIXTURES THEREOF, AT A TEMPERATURE OF FROM ATMOSPHERIC TO 400* F. AND RECOVERING A RESULTING CARBON BLACK HAVING A SUBSTANTIALLY REDUCED PH. 